Final answer:
It is true that you can double a drink recipe in a blender or shaker if it has sufficient capacity, considering adjustments for ingredients like ice and sugar that affect the total volume.
Step-by-step explanation:
The statement is true; when making two of the same drink, you can double the recipe if your blender or shaker has the capacity, and you adjust for differences in volume for ingredients like ice and sugar, which displace liquid. To illustrate this with an example involving sugar differences, imagine two full glasses of water. One glass has a single teaspoon of sugar, and the other has one-quarter cup of sugar. If both glasses are filled to the same level, the glass with less sugar (the teaspoon) actually contains more water since the quarter cup of sugar in the second glass displaces more water than the teaspoon in the first.